Inductance and capacity



June 13, 1933. H. A. EWEN INDUCTANGE AND CAPACITY Filed June 12, 1930 II l I I II INVENTOR HARRY ALEXANDER EWEN BY ATfoRNEY Patented June 13,1938 UNITED STATES "PATENT oFmc HARRY ALEXANDER WIN, OI snmnmn, ENGLAND,ASSIGNOB TO RADIO CORPORATION 01 AIIBIOA; A CORPORATION OF DELAWAREIIDUO'IAICI AND CAPACITY Application filed June II, 1080, lerlal Io.40,588, and in Great Britain has 14, 1988.

This invention relates to inductances and cap acities for use withelectrical resonant circuit arrangements, and has for its object toprovide a correcting arrangement where by undesired changes of ftemperature chan uency, due to in the e ements of an ordinary tunedcircuit or the like, may be compensated.

Accordin to this invention undesired change of requency in the'elementsof an ord inary tuned circuit or the like is compensated for byconnecting-into or associating with said circuit an auxiliary inductanceor ind uctances and/or a capacity or capacities which is or are soconstructed as to vary with temperature to an extent necessary to comnsate for the variation in the constants of t e main inductance andcondenser in the circuit to'be corrected.

Preferably the auxiliary device or devices is or are itself orthemselves variable, i. e.

- is of the type wherein the capacity or inductance at agiventemperature may be varied.

The invention is illustrated in the accompanying drawing; in which:

Figure 1 shows a condenser constructed in accordance with the presentinvention,

Figures 2 and 3 show a modification'of the arrangement shown in Figure1,

Fi ure 4 shows an open view 3 wit the closing removed,

of Figure Figure 5 shows acircuit arrangement including one of thecapacities shown in Figures l to 4 inclusive.

Figure 6 shows an inductance of constant characteristics, while;

Figure 7 shows a modification of the at rangement of Fi re 6.

Referring to denser suitable for use denser for carryin into efiect, thesai pair of conductive as an-auxiliary conthe present invention"condenser comprises a plates a, 6, located opite .onev another, saidlates being carried members whose cee ient of temperalgure 1 which showsa con-.

ture expansion is different. 'As shown, one plate is mounted upon acopper rod 0 or other rod having a relatively large temperatureexpansion coeflicient, while the other plate is mounted u on a frame (1of silica or other material 0 relativel low temperature expansioncoefficient. he late I) is fixed to the bottom of the pot-1i e carrier(1 of silica, while the copper rod passes throu h a fixing hole in across piece 0 car- 55 ried y the top of the carrier. The rod may befixed in any desired position by means of a set-screw f. With thisarrangement the capacity of the condenser will increase withtemperature. If the opposite efiect is desired, the electrode fixed tothe pot-like carrier may be arranged above the floor thereof or as shownin Figure 2 the floor may be omitted and the electrode fixed aboutmid-way along the wall. The electrode 6 is formed with a central holethrough which the rod 0 carrying the other plate a passes, so that saidother plate is on the side of the first plate remote from the crosspiece. The arrangement thus described, though capable of capacityadjustment by moving the copper rod in the cross piece, is notconvenient for tuning and is therefore most suitable for use in fixedtuned circuits. In a preferred construction shown in Figures 3 and 4whereby variable capacity is ob-- tained, concentric arcuate plates areemployed, one plate being fixed to the carrier 30 d of silica or thelike and the copper rod carrying the other plate being arranged to berotatable. The construction will be obvious from Figure 3. It will beseen that by rotating the rod 0 the capacity of the 35 condenserconstituted by the arcuate plates will be varied. This arrangement isvery suitable for correcting a circuit such as a 'wavemeter which can betuned to difl'erent circuit is shown diagrammatically in Figure 5.

In the modification shown in Figure 6, which shows an inductance coilsuitable for use in carrying out the invention a silica frame isemployed to support one end of the coi h the other end being carried bya rod J of copper or the like arranged to be clamped in an desiredposition in the frame as shown. ith this construction increase intemperature. increases the value of the inductance.

Figure '3 illustrates a modification of the arrangement shown in Figurein which induc ance coils h are employed, one earned the frame 51 andthe other i rod j, As shown any increase in iper-attire increases themutual inductance csite eiiect may be obtained by arranging coilsoutside the silica frame and the rod j being passed throu h a suitablepositioned hole in one wall 0 the frame i. e. by employing aconstruction analogous to that shown in Figure 2. It will be seen thatthe invention has the advantage that the main components of anoscillatory circuit to be corrected may be or standard desi n andconstructed of materials which whilst givin rise to changes due totemperature variations, are convenient or cheap for manufacturingprocesses or have other advantages such as li htness or strength whichare important or the purpose in view. It also enables an existingapparatus to be corrected where the requirements of service renders thisnecessar Having now particularly described and ascertained the nature ofmy said invention and in what manner the same is to be performed, ideclare that what I claim is 1. A. temperature compensating reactancecomprising asupporting member of silica, a reactance element, means forfastening said element at one terminal to said supporting member,metallic means, means for adjustably mounting said metallic means onsaid support, said metallic means having a co-eflicient of expansiondifferent than the co-efiicient of expansion of said support member, andmeans for fastening the other terminal of said reactance element to saidmetallic means.

2. A temperature compensating reactance comprising a silica support,housing an inductive reacts'nce element, means for fasone terminal 01"said reactance to said silica supper"; housing member, metallic meansadjustably mounted on said silica support housing, said last namedmetallic means havinga coeiiicient of expansion different than thecoeflicient of expansion of the silica support housing, and means forfastening the other terminal of said inductive rcactance to saidmetallic means.

oesri'een it and 11' though obviously the opferent coefiicient ofexpansion than said first named support whereby the efi'ect of a vchange in temperature on the physical character of-said reactant-e iscompensated.

' 4:. A temperature compensating variable condenser comprising a silicasupport hous ing, a fixed arcuate electrode supported within saidhousing, outside coi'mecting means for said fixed electrode, movablearcucte electrode supported on one end of a metallic rod, said metallicrod being adiustably supported from said silica support .iousing.

HARRY ALEXANDER EWEN.

